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sched: Move rq->idle_stamp up to the core

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idle_balance() modifies the rq->idle_stamp field, making this information
shared across core.c and fair.c.

As we know if the cpu is going to idle or not with the previous patch, let's
encapsulate the rq->idle_stamp information in core.c by moving it up to the
caller.

The idle_balance() function returns true in case a balancing occured and the
cpu won't be idle, false if no balance happened and the cpu is going idle.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: alex.shi@linaro.org
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1389949444-14821-3-git-send-email-daniel.lezcano@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Daniel Lezcano 2014-01-17 10:04:03 +01:00 committed by Ingo Molnar
parent e5fc66119e
commit 3c4017c13f
3 changed files with 16 additions and 11 deletions
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11
kernel/sched/core.c
View file

@ -2704,8 +2704,15 @@ need_resched:
pre_schedule(rq, prev);
if (unlikely(!rq->nr_running))
idle_balance(rq);
if (unlikely(!rq->nr_running)) {
/*
* We must set idle_stamp _before_ calling idle_balance(), such
* that we measure the duration of idle_balance() as idle time.
*/
rq->idle_stamp = rq_clock(rq);
if (idle_balance(rq))
rq->idle_stamp = 0;
}
put_prev_task(rq, prev);
next = pick_next_task(rq);

14
kernel/sched/fair.c
View file

@ -6531,7 +6531,7 @@ out:
* idle_balance is called by schedule() if this_cpu is about to become
* idle. Attempts to pull tasks from other CPUs.
*/
void idle_balance(struct rq *this_rq)
int idle_balance(struct rq *this_rq)
{
struct sched_domain *sd;
int pulled_task = 0;
@ -6539,10 +6539,8 @@ void idle_balance(struct rq *this_rq)
u64 curr_cost = 0;
int this_cpu = this_rq->cpu;
this_rq->idle_stamp = rq_clock(this_rq);
if (this_rq->avg_idle < sysctl_sched_migration_cost)
return;
return 0;
/*
* Drop the rq->lock, but keep IRQ/preempt disabled.
@ -6580,10 +6578,8 @@ void idle_balance(struct rq *this_rq)
interval = msecs_to_jiffies(sd->balance_interval);
if (time_after(next_balance, sd->last_balance + interval))
next_balance = sd->last_balance + interval;
if (pulled_task) {
this_rq->idle_stamp = 0;
if (pulled_task)
break;
}
}
rcu_read_unlock();
@ -6594,7 +6590,7 @@ void idle_balance(struct rq *this_rq)
* A task could have be enqueued in the meantime
*/
if (this_rq->nr_running && !pulled_task)
return;
return 1;
if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
/*
@ -6606,6 +6602,8 @@ void idle_balance(struct rq *this_rq)
if (curr_cost > this_rq->max_idle_balance_cost)
this_rq->max_idle_balance_cost = curr_cost;
return pulled_task;
}
/*

2
kernel/sched/sched.h
View file

@ -1158,7 +1158,7 @@ extern const struct sched_class idle_sched_class;
extern void update_group_power(struct sched_domain *sd, int cpu);
extern void trigger_load_balance(struct rq *rq);
extern void idle_balance(struct rq *this_rq);
extern int idle_balance(struct rq *this_rq);
extern void idle_enter_fair(struct rq *this_rq);
extern void idle_exit_fair(struct rq *this_rq);